Combined telephone receiver and transmitter.



PATENTED JUNE 28. 1904. J. G. HOLMSTRUM. COMBINED TELEPHONE RECEIVER AND TRANSMITTER.

APPLIUA'I'IOH FILED AUG. 14, 1903.

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PATENT GrrrcE.

COMBINED TELEPHONE RECEIVER AND TRANSMITTER.

SPECIFICATION formingpart of Letters Patent No. 763.755, dated June 28, 1904.

Application filed ugust 14,3903 Serial No. 169,480 (No model.)

To all whom it may concur/L.-

Be it known that l, Jonas Guxmu lloLus'rui'm. a subject of thc hing of Sweden and Norway, and a resiucnt of Stockholm. in the Kingdom of Sweden. have invented certain new and useful improvements iu'a Combined Telephone Receiver and 'lransmitter, of which the following is a specification.

This invention relates particularly to telephone instruments or apparatus in which the receiver and transmitter are mounted in the same casing: and it has for its object to prevent sounding in telephone which will be produced when the receiver and transmitter are placed in close proximity to each other.

In the accompanyingdrawings, which illustrate an embodiment of the invention, Figure 1 is a -seetional elevation of a telephone in strumcnt provided with the present invention; and Figs. 2 and 3 are views, partly in section. illustrating. sectional constructions of the casing.

in many constructions of telephone instruments it very necessary in practice to mount the receiver and the transmitter in the same casing. The great advantage that would be otherwise gained by such a combination is, however. in a great degree nullified by the. fact that where the two diaphragms are thus brought into near proximity the vibration of one influences the other, thus causing it also to vibrate, thereby producing the phenomenon known as the sounding of the telehone," which makes satisfactory telephoning ith such an instrument impossible. The intensity of this sounding is increased because the vibrations are transmitted not on] ythrough the stratum of air between the diaphragms, butalso through the material of the casing which incloses them. By the present invcn tion, now to be described with especial refercncc to Fig. l, the above-recited dilliculties are wholly removed by simple and reliable means. This consists, broadly speaking, in lilling m a great or less extent the space between the diaphragms. ordinarily tilled with stroy the vibrations. 'l'his substance is so disposed that. like a partuion. Ii divides the space between the diaphragms into two compartments wholly separated from each other and each containing a diaphragm. In other words, a partition of non-vibratingorsounddeadening material is inter mscd between the diaphragm, but is kept out of contact with the latter, To prevent the vibrations from passing to the other through the walls of the casing, the non-vibrating material is also, in the preferred form. applied to the inner surface of the wall of the casing, and suchsounddeadening material may be continuous with that forming the partition.

Referring now especially to Fig. l, 1 is the diaphragm of the transmitter. (3 is the diaphragmof the receiver. H designates the electromagncts. 2) designates the annular steel magnets. 10 is a chamber partly lilled with granular carbon, and 11 is the casing containing the above-named parts.

All of the features recited are known. 12 designates the non-vibrating material, which may be wax. paraliin, or the like. This material is sodisposcd as to formacomplete partition across the casing ll between the two diaphragms i and i and also to contact with the side walls of the casing 11.

'Fig. 2 shows the casing made in two parts 13 and 14, provided with flanges l5 and secured together by bolts 16. A ring 17. ot'india-rubber or the like. is clamped between the flanges to prevent the transmission 1-1" the vibrations from one section or part of the easing to the other. In this two-part casingthe material 12 will be employed as in l"ig. l: but it need not necessarily be in contact with the walls of the casing. as the rubber ring or gasket 17 obviates this requirement. There will besleeve-washers lmotiiulia-xgubher,(secu at the right in Fig. 2,) about the bolts and under the nuts and lmlt-heads to prevent the transmission of vibration through the bolts.

Fig. 3 shows also a two-part.casingconsisting ot'sections l3 and l-l,.boltcd togetherasin air, ith a substance adapted to deadcn or de- Fig. .2; but in this case the scctions have hottoms 19, and in lieu of arubber ring 17 there is a disk 20, of rubber or like material, between said bottoms.

By sound -deadening material as this phrase is herein used is meant a substance of a rath er soft elastic or plastic character su:h

as india-rub'oer. wax, paratiin, and the like.

which will absorb the vibrations and not transmit them. This excludes wood, metal, and the like, which will transmit sound waves or vibrations under the conditions herein eontemplated as well or better than air.

Having; thus desc ibed my invention, I claim 1. A telephoning instrument, having a casing, a receiver and a transmitter mounted in said casing, and a partition of sound-deadening material within the casing between the diaphragms of the receiver and transmitter and separating the same.

2. A telephoning instrument having a casing, a receiver and a transmitter mounted in said casing, and a partition of sound-deadening material between the (liaphragms of the receiver and transmitters and in (OIllAtCf with the walls of the casing.

3. A telephoning instrument having: a receiver and a transmitter mounted in the same casing in near proximity to each other, and

having a soft sound-deadening material dis-- posed in the casing in a manner to interrupt the transmission of vibrations from one diaphragm of the instrument to the other.

4. A telephoning instrument having a r( ceiver anti a transmitter mounted in the same casing, and a partition of wax within the cusing between the 'iiaphragms of the receiver and transmitter and completely separating: the

same.

In witness whereof I have hereunto signed my name in the presence of two subscribing witnesses.

Witnesses:

Eassr SVANQVIST, Ronau'r Arnnmisx. 

